1. Field of the Invention
The invention pertains to a module having several thermoelectric elements connected electrically in series, each of which consists of at least one n-layer and at least one p-layer of thermoelectric material, thus forming at least one pn-transition extending along a boundary layer, wherein a temperature gradient can be applied or detected between a hot side and a cold side of each thermoelectric element parallel to the boundary layer.
2. Related Art
The way in which thermoelectric elements work is based on the thermoelectric effect, referred to in the following as the Seebeck effect. The Seebeck effect involves the occurrence of an electrical voltage between two points of an electrical conductor or two differently doped semiconductors which are at different temperatures.
Heat can be converted directly into electrical energy by the use of a thermoelectric generator made up of several thermoelectric elements. The thermoelectric elements preferably are semiconductor materials doped in different ways, as a result of which the efficiency versus thermoelectric elements consisting of two different metals connected to each other at one end can be considerably increased. Commonly used semiconductor materials include Bi2Te3, PbTe, SiGe, BiSb, and FeSi2. To obtain sufficiently high voltages, several thermoelectric elements are combined into a module and connected electrically in series.
To increase the efficiency of a thermoelectric generator, a module of the general type in question comprising several thermoelectric elements connected electrically in series is described in EP 1 287 566 B1, the disclosure of which, especially as it pertains to the design of the thermoelectric elements and their thermoelectric materials, is explicitly included in the present application. Each of the individual thermoelectric elements consists of at least one n-layer and at least one p-layer of thermoelectric material, thus forming at least one pn-transition extending along a boundary layer. A temperature gradient is applied between the n- and p-layers parallel to the boundary layer. The pn-transition is formed essentially along the entire, preferably the longest dimension of, the n-layer and p-layer and thus essentially along the entire boundary layer. As a result of the temperature gradient along the large pn-boundary surface, a temperature difference develops along this elongated pn-transition between the two ends of a p- and n-layer package, as a result of which the efficiency of the thermoelectric elements is higher than that found in the prior art, which does not comprise a temperature gradient along and inside the pn-transition.